Thin substrate electrostatic chuck system and method

ABSTRACT

In various aspects of the disclosure, a semiconductor substrate processing system may include an electrostatic chuck for holding a semiconductor substrate attached to an electrically insulating carrier; and an AC power supply electrically coupled to the electrostatic chuck.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/709,521, entitled “THIN SUBSTRATE ELECTROSTATIC CHUCK SYSTEM ANDMETHOD”, filed on May 12, 2015, which in turn is a continuation of U.S.patent application Ser. No. 13/485,975, entitled “THIN SUBSTRATEELECTROSTATIC CHUCK SYSTEM AND METHOD”, filed on Jun. 1, 2012. Theabove-mentioned applications are hereby incorporated by reference in itsentirety for all purposes.

TECHNICAL FIELD

Various aspects of the disclosure relate generally to an electrostaticchuck used to secure substrates during semiconductor processing.

BACKGROUND

As part of the semiconductor device manufacturing process, it is oftennecessary to support, for instance, a semiconductor substrate that actsas a substrate for the various device layers built-up in the device.Often used is a device called a chuck. Mechanical chucks typicallyinclude some type of mechanical pin to hold the substrate. The problemwith this type of arrangement is that it can tend to damage the edges ofthe substrate. This problem is magnified when thin substrates are usedin the process. Therefore, it may be desirable to improve the ability tosupport thin substrates during the manufacturing process. This isespecially important for larger substrates, up to, for instance, 300 mmin size.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like reference characters generally refer to the sameparts throughout the different views. The drawings are not necessarilyto scale, emphasis instead generally being placed upon illustrating theprinciples of the invention. In the following description, variousaspects of the disclosure of the invention are described with referenceto the following drawings, in which:

FIGS. 1A-1B illustrate an electrostatic chuck;

FIG. 2A illustrates a silicon on glass structure in accordance with anaspect of the disclosure;

FIG. 2B illustrates an electrostatic chuck in accordance with anotheraspect of the disclosure;

FIG. 3 illustrates a system in accordance with another aspect of thedisclosure;

FIG. 4 illustrates a system component in accordance with another aspectof the disclosure;

FIG. 5 illustrates a system component in accordance with another aspectof the disclosure;

FIGS. 6A-6C illustrate system components in accordance with anotheraspect of the disclosure;

FIG. 7 illustrates a process in accordance with another aspect of thedisclosure.

FIG. 8 illustrates a silicon on glass structure in accordance withanother aspect of the disclosure;

FIG. 9 illustrates a calculation of applied voltage in accordance withan aspect of the disclosure; and

FIG. 10 illustrates another calculation of applied voltage in an aspectof the disclosure.

DESCRIPTION

In various aspects of the disclosure, electrostatic chucks may beprovided that may include a power supply. In one or more embodiments,the power supply may be an AC power supply. In one or more embodiments,the power supply may be a high-voltage power supply. Moreover, in afurther aspect, the high voltage power supply may be used in conjunctionwith thin semiconductor substrates. The thin semiconductor substratesmay be optionally supported on glass or other non-conducting carriers.The thin semiconductor substrates may range up to 300 mm in size, orgreater. Optionally, the power supply may be modified to better supporthigh-voltage operation without arcing. Optionally, the power cablingused may be modified to better support high-voltage operation. Inanother aspect of the invention, non-conducting carriers used to supportthin semiconductor substrates may be sputtered with a thin layer ofconductive material. Further, the system may be used for conventionalsemiconductor substrates as well as supported thin substrates.Optionally, the system is able to automatically detect the substratetype.

The following detailed description refers to the accompanying drawingsthat show, by way of illustration, specific details and aspects of thedisclosure in which embodiments may be practiced. These aspects of thedisclosure are described in sufficient detail to enable those skilled inthe art to practice certain embodiments. Other aspects of the disclosuremay be utilized and structural, logical, and electrical changes may bemade without departing from the scope of the invention. The variousaspects of the disclosure are not necessarily mutually exclusive, assome aspects of the disclosure can be combined with one or more otheraspects of the disclosure to form new aspects of the disclosure. Thefollowing detailed description therefore is not to be taken in alimiting sense, and the scope of the present invention is defined by theappended claims.

Various aspects of the disclosure are provided for devices, and variousaspects of the disclosure are provided for methods. It will beunderstood that basic properties of the devices also hold for themethods and vice versa. Therefore, for sake of brevity, duplicatedescription of such properties may be omitted.

The term “at least one” as used herein may be understood to include anyinteger number greater than or equal to one.

The term “a plurality of” as used herein may be understood to includeany integer number greater than or equal to two.

The terms “coupling” or “connection” as used herein may be understood toinclude a direct “coupling” or direct “connection” as well as anindirect “coupling” or indirect “connection”, respectively.

The terms “disposed over”, “located over” or “arranged over” as usedherein are intended to include arrangements where a first element orlayer may be disposed, located or arranged directly on a second elementor layer with no further elements or layers in-between, as well asarrangements where a first element or layer may be disposed, located orarranged above a second element or layer with one or more additionalelements or layers between the first element or layer and the secondelement or layer.

Electronic devices are typically built using semiconducting materials.The manufacturing process involves many steps, typically starting with abare semiconductor substrate. The semiconductor substrate material oftencomprises silicon, due to the range of conductivities available,durability, and relatively low cost of this material. Typical siliconsubstrates have a thickness of between 600-1000 μm, although thisthickness can vary widely. During processing, both in transfer betweenvarious pieces of machinery and during the actual processing step, thesubstrate must be held in place. This is typically done using a grippingarm including a chuck, which is used to hold the semiconductorsubstrate. As used herein, the term “semiconductor substrate” includesall substrates which may be used to manufacture semiconductor devicesincluding, without limitation, silicon, silicon on insulator (SOI),germanium, germanium/silicon, indium phosphide and gallium arsenidesubstrates, for example.

A chuck can take a number of different forms, including a mechanicalchuck (comprising pins to hold the substrate in place), a vacuum chuck(comprising a vacuum force to hold the substrate in place), or anelectrostatic chuck (comprising an electrostatic chuck to hold thesubstrate in place). Electrostatic chucks are described in more detailbelow.

FIG. 1 illustrates the operation of an exemplary electrostatic chuck.The electrostatic chuck 100 includes one or more electrodes 115 and adielectric 120. Dielectric 120 can comprise any number of materials,depending on the application. Exemplary dielectrics include alumina,quartz, sapphire, and polyimide, for instance. Electrostatic chuck 100is further connected to a high-voltage power supply 125. Power supply125 is used to supply a high voltage to electrodes 115.

Semiconductor substrate 130 is placed adjacent to chuck 100. Oncesemiconductor substrate 130 is in contact with chuck 100, power supply125 is activated, as shown in FIG. 1B. Activation of power supply 125induces a strong electric field in the region of electrodes 115. In thecase of the two-electrode design depicted in FIG. 1, this results inregions of positive and negative charge in chuck electrodes 115. Inareas of semiconductor substrate 130 across from the regions of positiveand negative charge in chuck electrodes 115, regions of opposing signare induced 135, resulting in a positive grip pressure 140 due to theopposing charges. Semiconductor substrate 130 is held in place throughgrip force 140.

Voltage is typically applied to the chuck electrodes 115 in one of twoways, either as a direct current (DC) or an alternating current (AC). DCsystems typically are slower than AC systems, due in part to slowerresidual charge dissipation in the substrate. Therefore, forapplications where high throughput is desired, an AC chuck may bepreferred. Moreover, as discussed further below, AC chuck systems enablesemiconductor substrate detection through the detection of AC clampcurrent. This is not available on DC systems as there is no clampcurrent due to the presence of the semiconductor substrate, which actsas a capacitive load. Note that the above electrostatic chuckdescription assumes that a conductive or semiconductive substrate ispresent.

However, due to market demands to decrease device size, especially withrespect to mobile electronic devices, as well as increasing demand forless power dissipation in electronic devices in general, especially invertically connected power electronic semiconductor devices, thethickness of semiconductor substrates has steadily decreased. A typicalthin semiconductor substrate may have a thickness of between 70-200 μm,for instance. As the thickness of semiconductor substrates hasdecreased, the difficulty in handling during processing due to thefragile nature of the thinner semiconductor substrates has increased.One method of dealing with the thinner semiconductor substrates has beento bond the semiconductor substrate to a support structure, forinstance.

An example of such a structure is illustrated in FIG. 2A. Asemiconductor substrate 200 is bonded to a layer of adhesive material210. Adhesive material 210 is polymeric, and it comprises a center layer211 with a tacky adhesive 212, 213 on both sides. One layer of adhesive213 is bonded to semiconductor substrate 200, and the other layer ofadhesive 212 is bonded to a support structure, referred to as a carrier230. Carrier 230 may comprise any material suitable for supporting thesemiconductor substrate. According to an aspect of the disclosure, thecarrier comprises glass. In an embodiment, the glass used isborosilicate glass. The structure formed by the semiconductor substrate,adhesive, and glass (carrier) is referred to herein as a“silicon-on-glass (SOG)” workpiece (assuming a silicon substrate is usedwith a glass carrier) although other names may be used in the art.

The SOG workpiece provides structural integrity, by providing a thicker,and hence more rugged, substrate for handling during processing.However, the glass carrier is not conductive. This tends to restrict SOGworkpieces to processes using substrate-handling methods that do notrequire the application of an electric field to the substrate, such asmechanical methods. These methods have certain drawbacks associated withthem, including the possibility of particle generation or damage to thesubstrate; they are slower and less reliable then electrostatic chucksystems; and mechanical clamping tools do not allow so-called “Quad modewafer processing” (e.g. different impact angles at implanter tools) orother types of back-side processing. Quad mode wafer processingapplications are discussed further below. As electrostatic methods donot induce contact with the edges of the semiconductor substrate andallow back-side processing, such as Quad-mode processing, it isdesirable to be able to use such methods with SOG workpieces.

A semiconductor substrate without or with a glass or other insulatingcarrier may, when placed adjacent to an electrostatic chuck 100 asillustrated in FIG. 1B and FIG. 2B, form a capacitor (where FIG. 1Billustrates an example of a semiconductor substrate 130 withoutinsulating carrier, and FIG. 2B illustrates an example of asemiconductor substrate 200 with insulating carrier 230). Thecapacitance can be estimated from certain properties of the insulatinglayer, according to the following relationship:

$\begin{matrix}{C = {ɛ_{0} \cdot ɛ_{r} \cdot \frac{A}{d}}} & (1)\end{matrix}$

where C is the capacitance; ε₀ is the vacuum permittivity; ε_(r) is the(material specific) relative static permittivity; A is the area ofoverlap between the plates forming the capacitor (according to theexamples illustrated in FIG. 1B and FIG. 2B, the semiconductor substrate130 or 200 and the electrodes 115); and d is the thickness of theinsulating layer or layer stack between the plates (for example, thethickness of layer 120 in FIG. 1B, or the thickness of insulating layerstack 250 formed by layers 213, 211, 212, 230, and 120 in FIG. 2B).

In case that a layer stack including a plurality of insulating layers isformed between the plates (for example insulating layer stack 250 formedby layers 213, 211, 212, 230 and 120 in FIG. 2B), and taking theproperties of the individual insulating layers into account, thecapacitance may be estimated according to the following relationship:

$\begin{matrix}{C = {ɛ_{0} \cdot A \cdot \left( {\frac{d_{1}}{ɛ_{r_{1}}} + \frac{d_{2}}{ɛ_{r_{2}}} + \frac{d_{3}}{ɛ_{r_{3}}} + \ldots \; + \frac{d_{n}}{ɛ_{r_{n}}}} \right)^{- 1}}} & (2)\end{matrix}$

where C, ε₀, and A are the same as above, and ε_(r) ₁ and d_(i) (i≦1≦n,n being the total number of insulating layers in the layer stack) arethe relative static permittivity and the thickness, respectively, of thei-th layer of the layer stack.

Applying a voltage to a structure having a capacitance C results in aforce, F (indicated as arrow 140 in FIG. 1B and FIG. 2B, for instance),that can be calculated using the following relation:

$\begin{matrix}{F = {\frac{u^{2}}{d} \cdot C}} & (3)\end{matrix}$

where F is the clamping force; u is the applied root mean square (RMS)AC voltage; d is the (overall) thickness of the insulating layer orlayer stack (for example, the thickness of layer 120 in FIG. 1B, or theoverall thickness of the layer stack formed by layers 213, 211, 212,230, and 120 in FIG. 2B; and C is the capacitance.

Substituting relationship (1) into relationship (3) results in thefollowing relationship:

$\begin{matrix}{F = \frac{u^{2} \cdot ɛ_{0} \cdot ɛ_{r} \cdot A}{d^{2}}} & (4)\end{matrix}$

From this, the voltage u required for a given clamping force F, certaindielectric material ε_(r), area of overlap A, and constant thickness ofinsulating layer d, can be calculated:

$\begin{matrix}{u = \sqrt{\frac{F \cdot d^{2}}{ɛ_{0} \cdot ɛ_{r} \cdot A}}} & (5)\end{matrix}$

For the purposes of this disclosure, the resulting RMS voltage (V_(rms))can be converted to peak to peak voltage (V_(pp)) by multiplying by1.75. It should be noted that in case that an insulating layer stackincluding a plurality of insulating layers is provided, relationship (2)may be substituted into relationship (3), which may yield a slightlymore complex expression for voltage u, as will be readily understood bythose skilled in the art.

Examples of graphs created using the relationship (5) for two differingglass carrier thicknesses appear in FIGS. 9 and 10. A plot of appliedvoltage versus clamping force required for a standard 300 mm siliconwafer is included on both Figures for reference.

For example, in an embodiment, an electrostatic clamping force of 6 N ormore is required for a conventional (thick) silicon substrate 300 mm insize. Moreover, the clamping force required to hold a given substratewith an electrostatic chuck is approximately linearly related to theweight of the clamped object. The weight of a silicon substrate with anattached 1 mm thick glass carrier is approximately 1.6 time the weightof a bare semiconductor substrate. Therefore the clamping force requiredfor a 300 mm substrate with an 1 mm glass carrier attached may begreater than 10 N. From FIG. 9, it may be estimated that a RMS (rootmean square) voltage of greater than or equal to about 3.4 kV,corresponding to a voltage of about 6 kV peak to peak, is required.Referencing FIG. 10, a similar calculation using a glass carrier with athickness of 0.3 mm (which weighs approximately 0.8 times the weight ofa conventional silicon substrate) yielded a minimum RMS voltage of about1 kV, corresponding to a voltage of about 1.75 kV peak to peak, tosupply the necessary minimum force of 4.8 N. Therefore, according tovarious aspects of the disclosure, electrostatic chuck may be capable ofproviding a voltage which supplies a clamping force adequate to clampsubstrates comprising a range of sizes and weights. In one embodiment,the substrate may comprise a 300 mm silicon substrate attached to aninsulating carrier.

FIG. 3 illustrates an electrostatic chuck system 300 according to anembodiment of the disclosure. System 300 includes a conventionalsubstrate handling system 301 for handling, for instance, semiconductorsubstrates. In an embodiment, the system is configured to handlesemiconductor substrates up to 300 mm in size, although in principle thecurrent system may be extended to larger substrates, thus thisembodiment should not be read to limit the size of substrate which maybe handled through this technique. The conventional substrate handlingsystem 301 is used to transfer substrates 305 to and from othersubstrate-processing equipment, for instance. The conventional substratehandling system is oriented perpendicularly, as illustrated in FIG. 3.The conventional substrate handling system 301 further includes anoptical sensing system 350.

The conventional substrate handling system 301 is coupled to vacuumchamber 320, and may be located within vacuum chamber 320. Inside vacuumchamber 320, and accessible to transfer arm (not shown) of conventionalsubstrate handling system 301, is an electrostatic chuck 325.Electrostatic chuck 325 is electrically connected to a high-voltagepower supply 340. Power supply 340 is attached to electrostatic chuck325 by high-voltage cables 335 which are routed into vacuum chamber 320through a vacuum feed-through 327. Further included within vacuumchamber 320 is a processing tool 345. The processing tool 345 maycomprise any number of processing tools, as discussed further below.

Power-supply 340 is further coupled to optical sensor 350 included insubstrate handling system 301. Optical sensor 350 comprises adiscrimination means 355 for analyzing reflected light. Several of thecomponents will now be discussed in greater detail.

FIG. 4 illustrates a non-electrostatic chuck 405 in accordance with anaspect of the disclosure. Non-electrostatic chuck 405 can be used ineither vacuum or non-vacuum environments. Non-electrostatic chuck 405can be used for both thin semiconductor substrates on glass carriers andfor conventional semiconductor substrates. Non-electrostatic chuck 405is a horizontally-oriented substrate-handling device. Non-electrostaticchuck 405 comprises pins 432 for stabilizing a workpiece 434 onnon-electrostatic chuck 405. In an embodiment, three pins 432 are usedto stabilize the workpiece 434, although one of the pins is not shown inFIG. 4 for reasons of clarity. In an embodiment, the workpiece 434 maybe configured as an SOG workpiece, including a semiconductor substrate430 attached to an insulating glass carrier 431, as shown.

The system further includes an optical sensing system. The opticalsensing system comprises an emitter 415 and a sensor 410. Emitter 415 isan RGB (red LED, green LED, blue LED) light source. Light source 415 isoriented toward the substrate surface. The optical sensing systemfurther comprises a sensor 410. Sensor 410 is used to distinguish thetype of substrate present. Light source 415 illuminates the outside edgeof SOG workpiece 434 when the workpiece 434 is brought into place, andsensor 410 detects the reflected light. SOG workpieces such as SOGworkpiece 434, in an embodiment, are manufactured to include a glasscarrier 431 that is slightly larger than the attached semiconductorsubstrate 430. In an embodiment, glass carrier 431 may be 1 mm larger indiameter than the attached semiconductor substrate 430. Light source 415is oriented so that the light from the light source 415 either passesthrough the glass carrier 431 at the edge of the SOG workpiece 434 andis reflected off of the non-electrostatic chuck 405, or it is reflectedfrom the surface of the non-electrostatic chuck 405, if no glass ispresent. The reflected light is detected by the sensor 410 in bothcases. Depending on the ratio of the various wavelengths of lightdetected, sensor 410 is able to distinguish whether the substrate(s)currently in the system are silicon or silicon-on-glass, for example.However, the details of the light discrimination process are notimportant for the purposes of this disclosure, and will not be discussedfurther. Sensor 410 is interfaced to the HV Power supply 440 through aninterface cable 460. Once sensor 410 has determined the type ofsubstrate entering the system, it signals HV power supply 440 of thetype of substrate. HV power supply 440 then switches to the propersupply voltage and to the proper substrate detection mode through thecurrent monitoring device prior to processing, as will be discussedfurther below.

FIG. 5 illustrates HV power supply 540 in accordance with an aspect ofthe disclosure. The power supply may be an AC power supply, for examplea 6-phase, high-voltage AC power supply in accordance with anembodiment. In an aspect of the disclosure, the power supply may providevoltages ranging from 500 to 10,000 volts, peak to peak. Power supply540 includes a high voltage DC to DC amplifier board 510 and a highvoltage AC 6-channel amplifier 520 for amplifying the generated 6-phasevoltage. The 6-phase voltage is generated using a control board and6-phase generator 530. Six-phase generator 530 is coupled to input 550from optical sensing system. Six-phase generator 530 is also coupled by550 to a conventional control system, which controls the voltage forclamping and declamping of substrates. The input 550 from the opticalsensing system is used as an input to control the voltage supplied bythe power supply. When the optical sensor senses, for instance, astandard silicon substrate in position for insertion into the vacuumprocessing system, the HV power supply will output a voltage compatiblewith such a substrate. In an embodiment, the voltage will be set to 2000V peak to peak for a standard silicon substrate. In another embodiment,the voltage is set to a higher voltage when a SOG workpiece ispositioned for entry into the system. In an embodiment, the voltage willbe set to a range of 6000-8000 volts peak to peak, for instance. Thevoltage used will vary widely, and also higher voltage could berequired. In an embodiment, the voltage may range as high as 10,000Volts peak to peak, or higher. In a further embodiment, switching may becontrolled through manual means, such as a bayonet switch on a panel,for instance.

The power supply further includes a high-voltage terminal 560. Thehigh-voltage terminal 560 may be constructed of materials which canwithstand the high AC voltages generated by power supply 540.

The HV terminal 560 is further connected to high voltage cables 535. Inan embodiment, HV terminal is a high-voltage (15 kV) BNC connector, andthe high-voltage cables 535 are also specified to 15 kV. High voltagecables 535 are used to connect the high voltage power supply to thevacuum chamber (not shown in FIG. 5). As with the other components usedin the object of the disclosure, the cables, and the harness used toroute and contain the cables, may be constructed in such a way as toallow the use of voltages up to 15 kV. The high voltage cables 535 areconnected to the vacuum system through a vacuum feed-through 527, whichalso may be certified to 15 kV.

Power supply 540 further includes a clamp current monitoring device 532.Clamp current monitoring device 532 is used to monitor the currentapplied to the electrostatic chuck, for instance. Current information isused to provide information about the presence or absence of a substrateon the electrostatic chuck to the conventional control system. Theinterlock is used to avoid, for instance, implant processing withoutsubstrate on electrostatic chuck.

FIG. 6 illustrates an electrostatic chuck 606 in accordance with anaspect of the disclosure. Electrostatic chuck 606 comprises a mount 602that is vertically translatable (indicated by arrow 617 in FIG. 6).Mount 602 may further be tilted upwards and downwards (indicated byarrow 619 in FIG. 6) about the y-axis to better facilitate implantationof ions, for instance. Even further, mount 602 may be rotatably movedabout the z-axis (indicated by arrow 621 in FIG. 6). Moreover,electrostatic chuck 606 may also be rotated 360 degrees about itscentral axis (indicated by arrow 622 in FIG. 6). The electrostatic chuck606 is attached to the mount 602.

As illustrated in 6B, the electrostatic chuck 606 may further comprise agas cooling system 613. The gas cooling system 613 comprises a pluralityof passages 613 running throughout the electrostatic chuck 606. Passages613 terminate in holes 641 in the face of the electrostatic chuck 606.Gas may be supplied through the holes 641 to cool an attached substrateduring processing. However, the use of gas during use of thehigh-voltage electrostatic chuck 606 with a SOG workpiece may result inelectrical arcing. Therefore, in an aspect of the disclosure, the gascooling system may be disabled when using the electrostatic chuck systemwith a SOG workpiece or other non-conducting carrier configuration, forinstance.

As shown in expanded view 6C, electrostatic chuck 606 further comprisesa connection terminal 626. Connection terminal 626 comprises a firstinsulating layer 631 enclosing electrical terminals 633 and separatinghigh voltage connection plugs (not shown) from electrostatic chuck 606.In an aspect of the disclosure, first insulating layer 631 comprisessilicone. Moreover, in a further aspect of the disclosure, a furtherinsulating layer 632 is provided between the first insulating layer 631and the electrostatic chuck 606. Further insulating layer 632 may beformed from epoxy resin with hardener composite, for instance. Furtherinsulating layer 632 is advantageous because of the very high voltagesused for various embodiments. Further insulating layer 632 may be formedfrom other materials suitable for high voltage insulating including, butnot limited to, liquid silicone or polyimide, for example.

Now, a process flow according to an aspect of the disclosure will bedescribed. Process flow is described with reference to FIG. 7.

At 701, substrates are loaded into the substrate-handling system.Substrates may comprise either standard semiconductor substrates, orthin semiconductor substrates, for example. As discussed above, if thinsilicon substrates are used, they will often be attached to a rigidcarrier, such as a glass carrier, although the embodiments are notlimited to glass. However, the various aspects of the disclosure includeboth conducting and non-conducting support carriers, and the disclosureshould not be read as being limited to any particular support material.

The substrate-handling system includes a separate mechanical chuck fortransporting the substrate. The mechanical chuck comprises projectionsfor stabilizing the substrate. The mechanical projections contact thinsubstrates only on the glass carrier portion of the SOG workpiece.Moreover, the mechanical projections do not grasp the glass carrier, tominimize the potential for damage to the glass carrier. Rather, theymerely stabilize the substrate as it rests in the mechanical chuck.During the horizontal substrate-handling phase, the substrate onlycontacts parts made either of silicone or polyethylether ketone (PEEK),thus minimizing the risk of damage or contamination.

At 705, and prior to transfer into the vacuum chamber, the silicon orSOG workpiece is inspected using an optical sensing tool. The opticalsensing tool uses light in the RGB range, for example. Optical sensingtool emits light in the appropriate frequency range, and the lighteither passes through glass carrier and is reflected off of the chuck,or it is reflected off of the chuck without passing through glass,depending on the type of substrate present. Optical sensing tool thendetects the frequency of light reflected off of the surface of thesubstrate. The detected light is separated and detected according tofrequency. The ratio of the frequencies of light is used to identify thetype of substrate present. The sensor identifies the type of substrateaccording to previously defined criteria, and sends a signal to the highvoltage power supply indicating what type of substrate is associatedwith a given position in the substrate handling system.

Based upon the signal, the high-voltage power supply and clamp currentmonitoring is then configured to output a certain voltage at step 715 or716. In this way, the signal from optical sensor is used as an input toan interlock. The interlock is used to prevent the accidentalapplication of high voltage to the incorrect type of substrate.Application of too high a voltage to a typical silicon substrate, forinstance, could result in arcing, which could potentially damage thesubstrate and electrostatic chuck, possibly rendering the systemuseless.

At 710, substrate or SOG substrate is passed into the vacuum chamber forprocessing. The vacuum chamber may include any number of tools forprocessing substrates. In an embodiment, the chamber comprises animplant tool. The implant tool uses high voltages to implant atomicimpurities into the substrate in doping processes. The species implantedmay include boron (B), phosphorous (P), and arsenic (As) and hydrogen,for instance. However, the species implanted under this method are notlimited by the disclosed electrostatic chuck, and thus should not beviewed as limiting. Any species that may be implanted using previouslyknown substrate support mechanisms may be implanted using theelectrostatic chuck disclosed herein.

The vacuum system further includes an electrostatic chuck in accordancewith an aspect of the disclosure. As described above, electrostaticchuck is translatable in the X, Y and Z-directions. It is also tiltablein thus allowing angled implants of atomic species. Moreover,electrostatic chuck can also be rotated 360 degrees about the centralaxis of the substrate. This combination of movement allows forflexibility in the choice of implant locations.

Substrate is held in position by electrostatic forces according toaspects of the disclosure. As discussed above, a voltage ofapproximately 2000 V peak to peak is adequate to retain a standardsilicon substrate on electrostatic chuck. If a standard siliconsubstrate was detected at step 705, a voltage of 2 kV peak to peak maybe applied to the electrostatic chuck, as shown in step 716. However, inthe case of a glass-mounted thin silicon substrate, a much highervoltage is needed due to the non-conducting nature of the glass carrier.Therefore, in an embodiment, at step 715 a voltage of approximately 6-8kV peak to peak may be required for a thin silicon substrate having a 70μm thickness mounted on an insulating (for example, glass) carrier.However, as discussed above, this voltage may vary widely, depending onapplication and nature of the insulating carrier. A thicker insulatingcarrier may require a higher voltage, for instance. Conversely, athinner insulating carrier may require a lower voltage. Moreover, thedisclosed embodiment is merely exemplary, and is not limited toinsulating carriers comprising glass. The current disclosure is broadlyapplicable to all insulating carriers.

Electrostatic chuck allows for the processing of substrates at a varietyof angles. This allows for high-angle implants on the backside ofsubstrate, for instance. In an aspect of the disclosure, electrostaticchuck is used in conjunction with ion beam device to enable a Quadimplant at step 720, for example.

In a Quad implant at step 720, substrate is tilted a high angle withrespect to ion implantation device. In an aspect of the disclosure, theangle may be 45 degrees with respect to the ion implantation device, asshown in FIG. 6A. Following implantation, substrate is rotatedapproximately 90 degrees about its central axis. Substrate is furthertilted to the same angle as used in the previous implantation step.Following rotation, a second implatation step is performed. In an aspectof the disclosure, the dose of a second implantation is performed. In anembodiment, the dose of the second implantation step is substantiallyequal to that of the first implantation step. This procedure isperformed two more times, until a total of four rotation/implantationsteps have been performed.

Moreover, in another aspect of the disclosure, electrostatic chucksystem allows for a higher angle of implantation on siliconsubstrate-on-glass systems. Previous systems were limited to eithermechanically clamped systems or to batch systems, which rely oncentrifugal force to hold such substrates into place. The mechanicalsolution could potentially damage the substrate, as discussed above. Thebatch solution, while having the potential benefit of being less likelyto cause damage, was limited in the extent that one could angle thesubstrate. The current disclosure, however, is not so limited.

As illustrated in FIG. 8, in another exemplary embodiment, metal issputtered onto the glass carrier prior to bonding the thin siliconsubstrate to the glass carrier. This improves the conductivity of theglass carrier, thus improving the retention of the glass or othernon-conducting support onto the electrostatic chuck.

As illustrated in FIG. 8, in this embodiment the glass carrier 811 issputtered with a metal oxide 870, such as indium tin oxide (ITO), forinstance. These oxides, or metals or metal oxides of similar properties,have certain advantages. They are electrically conducting, yet stilltransmissive to optical wavelengths of light, for instance. Use of aconducting material may allow for an increase in the amount of chargepresent at the electrostatic chuck/substrate interface, for instance,resulting in an increased retention force being applied to thesubstrate, for instance. Moreover, the ability of the material totransmit light may be advantageous for the application of light throughthe sputtered oxide film to the adhesive film, for instance,facilitating the removal of the adhesive film.

In the embodiment illustrated in FIG. 8, a conductive film 870, forexample an ITO film 870, has been deposited on the glass carrier 811.The glass carrier 811 and film 870 are attached to semiconductorsubstrate 800 (for example, by an adhesive layer or layer stack 813, asshown), thus forming an SOG workpiece 830, in the case of semiconductorsubstrate 800 being formed of silicon. SOG workpiece 830 is positionedonto electrostatic chuck 806 so that the conductive film (e.g. ITO film)870 is closest to electrostatic chuck 806. When a high voltage isapplied to electrostatic chuck 806, the thin conductive film 870 allowsfor the greater electron migration to the surface of the film, thusallowing a greater induced charge at the surface. This results ingreater adhesion of the glass carrier 811 to the electrostatic chuck806. Processing proceeds normally from here.

A person skilled in the art will recognize that combinations of theexemplary embodiments described herein may be formed. For example, aconfiguration as the one shown in FIG. 2B or FIG. 4 may be employed withor without an applied conductive film deposited on the carrier 230, 431.Similarly, some or all aspects of the disclosure may be employed eitherin air or under vacuum, for instance. Moreover, the electrostatic chuckmay be passed from tool to tool, along with the attached substrate.Moreover, the optical sensing device illustrated and discussed in FIGS.3, 4, and 7 may be incorporated into the same vacuum chamber as theprocessing tool(s). Also, the electrostatic chuck and method for usedisclosed herein are applicable to other types of substrates includingconductive and non-conductive surfaces, such as flat panel displays, forinstance.

A processing system in accordance with various embodiments may include:an electrostatic chuck for holding a semiconductor substrate attached toan electrically insulating carrier, wherein the electrically insulatingcarrier is disposed between the electrostatic chuck and thesemiconductor substrate; an AC power supply electrically coupled to theelectrostatic chuck; wherein the supplied voltage is dependent on atleast one property of the electrically insulating carrier.

In accordance with an embodiment, the AC power supply may provide avoltage of at least 500 V peak to peak.

In accordance with another embodiment, the at least one property of theelectrically insulating carrier may include thickness of theelectrically insulating carrier.

In accordance with another embodiment, the thickness may be at least 0.2mm.

In accordance with another embodiment, the at least one property of theelectrically insulating carrier may include the material used to formthe electrically insulating carrier.

In accordance with another embodiment, the supplied voltage may befurther dependent on the weight of the semiconductor substrate andelectrically insulating carrier.

In accordance with another embodiment, the system may further include aprocessing tool.

In accordance with another embodiment, the processing tool may be animplant device.

In accordance with another embodiment, the AC power supply may be a6-phase high voltage AC power supply.

In accordance with another embodiment, the supplied voltage may be atleast 3 kV peak to peak, for example in the range from about 6 kV toabout 8 kV in accordance with another embodiment.

A processing system in accordance with various embodiments may include:an electrostatic chuck for holding a semiconductor substrate attached toan electrically insulating carrier, wherein the electrically insulatingcarrier is disposed between the electrostatic chuck and thesemiconductor substrate; an AC power supply electrically coupled to theelectrostatic chuck wherein the AC power supply provides a voltage of atleast 500 V peak to peak.

In accordance with an embodiment, the supplied voltage may be at least 1kV peak to peak.

In accordance with another embodiment, the supplied voltage may bedependent on a thickness of the electrically insulating carrier.

In accordance with another embodiment, a thickness of the semiconductorsubstrate may be less than or equal to about 200 μm.

In accordance with another embodiment, a thickness of the semiconductorsubstrate may be less than or equal to about 100 μm.

In accordance with another embodiment, the supplied voltage may bedependent on a material used to form the electrically insulatingcarrier.

In accordance with another embodiment, the supplied voltage may befurther dependent on the weight of the semiconductor substrate andelectrically insulating carrier.

In accordance with another embodiment, the system may further include aprocessing tool.

In accordance with another embodiment, the processing tool may be animplant device.

In accordance with another embodiment, the AC power supply may be a6-phase high voltage AC power supply.

In accordance with another embodiment, the supplied voltage may be atleast 3 kV peak to peak, for example in the range from about 6 kV toabout 8 kV in accordance with another embodiment.

A method of manufacturing a device in accordance with variousembodiments may include: providing a semiconductor substrate; attachingthe semiconductor substrate to an electrically insulating carrier;supporting the semiconductor substrate and electrically insulatingcarrier with an electrostatic chuck, the electrically insulating carrierbeing disposed between the electrostatic chuck and the semiconductorsubstrate; wherein a voltage supplied to the electrostatic chuck isrelated to at least one property of the electrically insulating carrier.

In accordance with an embodiment, attaching the semiconductor substrateto the electrically insulating carrier may include attaching thesemiconductor substrate such that a front side of the semiconductorsubstrate faces the electrically insulating carrier.

In accordance with another embodiment, the at least one property may bea thickness of the electrically insulating carrier.

In accordance with another embodiment, the at least one property may bethe material used to form the electrically insulating carrier.

In accordance with another embodiment, the voltage supplied to theelectrostatic chuck may be a high voltage.

In accordance with another embodiment, the high voltage may be at least500 V peak to peak.

In accordance with another embodiment, the high voltage may range from6-8 kV peak to peak. In other words, the high voltage may be in therange from 6 kV to 8 kV peak to peak.

In accordance with another embodiment, the electrically insulatingcarrier may further include a conductive layer. In an embodiment, theconductive layer may, for example, be disposed over a side of theelectrically insulating carrier facing the electrostatic chuck.

In accordance with another embodiment, the conductive layer may beoptically transmissive.

In accordance with another embodiment, the semiconductor substrate maybe a 300 mm substrate, for example a 300 mm wafer in accordance withanother embodiment.

In accordance with another embodiment, the method may further includeimplanting the substrate.

In accordance with another embodiment, the implanting may be doneaccording to a Quad implant process.

In accordance with another embodiment, the implant process may be abackside implant process.

While the invention has been particularly shown and described withreference to specific aspects of the disclosure, it should be understoodby those skilled in the art that various changes in form and detail maybe made therein without departing from the spirit and scope of theinvention as defined by the appended claims. The scope of the inventionis thus indicated by the appended claims and all changes which comewithin the meaning and range of equivalency of the claims are thereforeintended to be embraced.

What is claimed is:
 1. A processing system, comprising: an electrostaticchuck configured to hold a workpiece; and an AC power supplyelectrically coupled to the electrostatic chuck wherein the AC powersupply is configured to provide a first voltage when the workpiece is afirst-type workpiece and a second voltage when the workpiece is asecond-type workpiece, the first voltage being higher than the secondvoltage, the first-type workpiece comprising a first semiconductorsubstrate and an electrically insulating carrier disposed between theelectrostatic chuck and the first semiconductor substrate, thesecond-type workpiece comprising a second semiconductor substrate andlacking said electrically insulating carrier; wherein the workpiece isheld against the electrostatic chuck by an electrostatic force generatedby the provided voltage.
 2. The processing system of claim 1, whereinthe electrically insulating carrier has a thickness of at least 0.2 mm.3. The processing system of claim 1, further comprising an opticalsensing system configured to distinguish between the first-typeworkpiece and the second-type workpiece.
 4. The processing system ofclaim 1, wherein the first voltage is at least 3 kV peak to peak.
 5. Theprocessing system of claim 1, wherein the first voltage is from about 6kV to about 8 kV peak to peak.
 6. The processing system of claim 1,further comprising a gas cooling system, the gas cooling system beingdisabled when the workpiece is the first-type workpiece and the gascooling system being enabled when the workpiece is the second-typeworkpiece.
 7. The processing system of claim 1, wherein the firstsemiconductor substrate is the same as the second semiconductorsubstrate.
 8. The processing system of claim 1, wherein the electricallyinsulating carrier comprises glass.
 9. A method of manufacturing adevice, the method comprising: providing a workpiece; and supporting theworkpiece with an electrostatic chuck; wherein the workpiece is heldagainst the electrostatic chuck by an electrostatic force generated by avoltage supplied to the electrostatic chuck; wherein the voltagesupplied to the electrostatic chuck is a first voltage when theworkpiece is a first-type workpiece and a second voltage when theworkpiece is a second-type workpiece, the first voltage being higherthan the second voltage, the first-type workpiece including a firstsemiconductor substrate and an electrically insulating carrier attachedto the first semiconductor substrate, the second-type workpieceincluding a second semiconductor substrate and lacking the electricallyinsulating carrier; wherein, when the workpiece is the first-typeworkpiece, the electrically insulating carrier of the first-typeworkpiece is disposed between the first semiconductor substrate and theelectrostatic chuck.
 10. The method of claim 9, further comprising:optically sensing the workpiece to determine whether the workpiece isthe first-type workpiece or the second-type workpiece.
 11. The method ofclaim 9, further comprising: disabling a gas cooling system when theworkpiece is the first-type workpiece and enabling the gas coolingsystem when the workpiece is the second-type workpiece.
 12. The methodof claim 9, wherein the electrically insulating carrier has a thicknessof at least 0.2 mm.
 13. The method of claim 9, wherein the first voltageis at least 3 kV peak to peak.
 14. The method of claim 9, wherein thefirst voltage is from about 6 kV to about 8 kV peak to peak.
 15. Themethod of claim 9, wherein the first semiconductor substrate is the sameas the second semiconductor substrate.
 16. The method of claim 9,wherein the electrically insulating carrier comprises glass.
 17. Aprocessing system, comprising: an electrostatic chuck configured to holda workpiece; an optical sensing system configured to determine a type ofthe workpiece; and an AC power supply electrically coupled to theelectrostatic chuck wherein the AC power supply is configured to providea voltage depending upon the type of the workpiece; wherein theworkpiece is held against the electrostatic chuck by an electrostaticforce generated by the provided voltage.
 18. The processing system ofclaim 17, wherein the AC power supply provides a first voltage when theworkpiece is a first-type workpiece and a second voltage when theworkpiece is a second-type workpiece, the first voltage being higherthan the second voltage, the first-type workpiece comprising a firstsemiconductor substrate and an electrically insulating carrier disposedbetween the electrostatic chuck and the first semiconductor substrate,the second-type workpiece comprising a second semiconductor substrateand lacking the electrically insulating carrier.
 19. The processingsystem of claim 18, wherein the electrically insulating carrier has athickness of at least 0.2 mm.
 20. The processing system of claim 18,wherein the first voltage is at least 3 kV peak to peak.
 21. Theprocessing system of claim 18, wherein the first voltage is betweenabout 6 kV to about 8 kV peak to peak.
 22. The processing system ofclaim 18, further comprising a gas cooling system, wherein the gascooling system is disabled when the workpiece is the first-typeworkpiece and the gas cooling system is enabled when the workpiece isthe second-type workpiece.
 23. The processing system of claim 17,wherein the first semiconductor substrate is the same as the secondsemiconductor substrate.
 24. The processing system of claim 17, whereinthe electrically insulating carrier comprises glass.
 25. The processingsystem of claim 17, wherein the electrically insulating carrier has athickness of at least 0.2 mm.
 26. A method of manufacturing a device,comprising: providing an electrostatic chuck and a workpiece, the chuckconfigured to hold the workpiece; optically sensing a type of theworkpiece; and causing an AC power supply to provide a voltage dependingupon the type of the workpiece; wherein the workpiece is held againstthe electrostatic chuck by an electrostatic force generated by theprovided voltage.
 27. The method of claim 26, wherein the workpiece is afirst-type workpiece including a first semiconductor substrate and anelectrically insulating carrier attached to the first semiconductorsubstrate, or a second-type workpiece including a second semiconductorsubstrate and lacking the electrically insulating carrier.
 28. Themethod of claim 26, wherein when the type of the workpiece is sensed tobe a semiconductor substrate attached to an electrically insulatingcarrier, the voltage provided is at least 3 kV peak to peak.
 29. Themethod of claim 26, wherein when the type of the workpiece is sensed tobe a semiconductor substrate attached to an electrically insulatingcarrier, the voltage provided is between about 6 kV and about 8 kV. 30.The method of claim 27, wherein the electrically insulating carrier hasa thickness of at least 0.2 mm.
 31. A processing system, comprising: anelectrostatic chuck configured to hold a workpiece, the workpiececomprising a semiconductor substrate attached to an electricallyinsulating carrier, wherein, when the electrostatic chuck holds theworkpiece, the electrically insulating carrier of the workpiece isdisposed between the electrostatic chuck and the semiconductor substrateof the workpiece; and an AC power supply electrically coupled to theelectrostatic chuck wherein the AC power supply is configured to providea voltage from about 6 kV to about 8 kV peak to peak; wherein theworkpiece is held against the electrostatic chuck by an electrostaticforce generated by the provided voltage.
 32. The processing system ofclaim 31, wherein the electrically insulating carrier comprises glass.33. A method of manufacturing a device, the method comprising: providinga semiconductor substrate; attaching the semiconductor substrate to anelectrically insulating carrier, thereby forming a workpiece; supportingthe workpiece, which comprises the semiconductor substrate and theelectrically insulating carrier, with an electrostatic chuck, theelectrically insulating carrier of the workpiece being disposed betweenthe electrostatic chuck and the semiconductor substrate of theworkpiece; wherein the workpiece is held against the electrostatic chuckby an electrostatic force generated by a voltage supplied to theelectrostatic chuck; wherein the voltage supplied to the electrostaticchuck is at least 3 kV peak to peak.
 34. The method of claim 33, whereinthe voltage supplied to the electrostatic chuck is in the range fromabout 6 kV to about 8 kV peak to peak.
 35. The method of claim 33,wherein the electrically insulating carrier comprises glass.